This manifesto for video on the web was first published on February 28, 2007. That day, Opera proposed the video element, and Opera showing Ogg Theora natively was demonstrated at the Browser War: Episode II event. (Blogged here:
123456) A few weeks later, I gave a Google Tech Talk on the same subject.

A call for video on the web

It's time to make video a first-class citizen of the web. We, the
users, have video cameras in our pockets and the bandwidth to tranfer
more clips and streams than we can watch. What's missing is a an easy
way to integrate video into web pages, and native support for video in
browsers. We, the web community, should address this by adding a video
element to HTML:

<video src="demo.ogg">

In addition to giving video an HTML element, we must also agree on
a baseline video format that will be universally supported, just like
the GIF, JPEG and PNG image format are universally supported. It's
important that the video format we choose can be supported by a wide
range of devices an that it's royalty-free (RF). RF is a
well-establish principle for W3C standards.

At Opera, we have built an experimental
version that has native support for Ogg Theora. For now, it is
only available on Windows. NOTE! Do not choose to start Opera in the
installation process. After installing, exit the installation process
and start the the experimental build manually.

Also, the video files on
Wikipedia can be seen through the <video> element. Select any
video file, and click on "Play in browser". If you are using the
experimental Opera build, you should now see video played natively.